function scroll(event) {
        if (event.wheelDelta > 0) //wheel up
                navigationList(SLIDE_RIGHT);
        else
                navigationList(SLIDE_LEFT);
}

function navigationList(event) {

		var e = event || window.event;
        var code = e.keyCode || e;
        switch (code) {
                case BACK:
                        if (!isFirstPage)
                                history.back();
                        break;
                case SK_NW:
                        leftTopSoftKey();
                        break;
                case SK_NE:
                        rightTopSoftKey();
                        break;
                case SK_SW:
                case SK_SW_2:
                        leftBottomSoftKey();
                        break;
                case SK_SE:
                case SK_SE_2:
                        rightBottomSoftKey();
                        break;
                case VOLUME_UP:
                        break;
                case VOLUME_DOWN:
                        break;
                case PTT:
                        startSpeechInput();
                        break;
                default:
                        console.info('unkown key pressed. ignoring: ' + e.keyCode);
                        break;
        }
}